Method of making pneumatic tires



April 17, 1928.

H. M. LAMBERT METHOD 0F MAKING PNEUMATIC TIRES ATTORNEY M MM Filed May 25, 192'? Patented Apr. 17, 192s. i

UNITED STATES HENRY M. LAMBERT, F PORTLAND, OREGON; HELEN H. LAMBERT EXECUTBIX OEv My invention mms3 L PATENT oFF-TCE.

sAInHnNaY n. LAMBERT, DECEASED.

METHOD 0F MAKING PNEUMATIC has for its object to provide 'method of manufactur particularly those hav- Heretofore, it

Ilias been the practice to build up the tire carcass of rubber and textile material, placev a thick slab of tread stock around the periphery ofthe carcass, then place the same in a mold with core pins around the slab of rubber and form the tread holes by the use of an air bag to inflate ythe carcass and squeeze the tread rubber radially to cause it to flow between and around the core pins.

Such method. is

not always result inperfect tires,

somewhat costly and it does the tires occasionally separating adjacent to the holes.

My invention therefore has for its prime object the provision of a method which will not only reduce the cost of manufacture but will result in the production of more uni-- formly vperfect Generically the present invention 1n first building a tire carcass-according to tires.

consists any of the methods now in vogue and then placing a sufficient quantity of tread rubber `on the periphery quired in the finished tire.

of the tire as may be re- The carcass with the applied tread stock is placed in a vulcanizing mold,

serted.

anv air bag being first in- Themold is then closed and the air.

bag infiated toa pressure slightly in excess of the atmosphere and sufficient to hold the tread stock within the tread forming cavity portion of the substantially fill the same.

molding chamber so as to Then hole or recess forming pins yare forced into the tread stock, but before forcing the pins into the tread-stock I preferably apply sufficient heat to the mold to rubber, thus re and permitting begin the softening of the ndering the rubber pliable an easier penetration of the pins and the consequent displacement'of the rubber to form are forced into stock, the tread course, moved inwardly or somewhat tened. As soon, however, f placed the air bag flation pressure cass 1s squeezed the tread stock the apertures. `As the pins place and displace the tread portion of the carcass is, of

as the pins are is brought up to full inwith the result that the caroutwardly at the tread and is forced into tight engage.

ment withv the walls of the molding cavity,

the mass being compacted and air bubbles pressed out, thus ensuring a perfect union between the par ts .of the tire. This pressurel flatcenter of the molding cavity against 'the tread stock, which ensures the formation of a full tread without air pockets, etc.

As soon as vulcanization has been completed the pins .are withdrawn,

the usual manner.

In the accompanying drawings Il have illustrated ,diagrammatically the steps vernployed to constitute my process, and by refelrlence to th drawing it will be observed t at Figure 1 is a cross'section of a tire carcass built up with the tread 'stock in. placeprior to. introduction into the vulcanizing mold.

Figure 2 is .a detail lcross section of a vulcanizing mold with the tire .carcass of Figure 1 in place and the air bag partly inflat-ed.

Figure 3 is a view similar to Figure 2 after the core pins have been pressed into place.

Figure 4 is a view similar to Figure 3 after the ai bag has been fully inflated.

Figure is a sectional perspective view of a portion of the finished tire.

In the drawings,Y in which like numerals indicate like parts in all of the figures, 1 is t-he mold which may be of the usual type and is provided with the molding chamber 2 and the steam jacket chamber 3. i

4 designates the core pins which may be carried by a ringr 5 and inserted through apertures in thc side walls of the mold, the mold, of course, being of the two-part or split type.

' 6 indicates the carcass of rubber and rubberized textile material (fabric, cord, or a combination of, fabric and cord) and 7 represent-s the tre-ad rubber stock.l

The air bag is indicated by the reference character 8 and the transverse holes in the finished t-ire (Figure 5) are indicated by 9.

As before intimated in applying my method the c arcass 6 `is built up on a form in any of the usual ways and sufficient tread rubber is placed around the periphery of the carcass to form the. required tread of the. tire.

This structure is then placed in the mold 41 (after, of course, inserting the air bag 8) and the mold is closed, it being, of course, understood that at this timelthe pins 4 are the mold opened and the t1re and air bag removed in msl Air is then 4placed in the air bag at'a 'sufficient pressure -lwalls and of ventilated pneumatic pins have been to hold the carcass in contact with the mold of the mold chamber 2. Then steam may be Aadmitted into the chamber to warm the rubber to a sufficient degree to render it plastic and the pins 4 are forced home. As the pins 4 are forced into the rubber a corresponding volume of rubber will be displaced, with the result that the carcass will be flattened some- Wliatat its crown or periphery, as indicated in Figure 3. The full air pressure is then introduced into the `air bag` and asvthe carcass cannot move laterally and as the pressure's of air actually tend to produce a circular cross sectionof the carcass the greatest pressure will be active against the tread of the tire and will ensure the tread rubber flowing into all of the interstices of the walls of fthe rubber molding cavity, displacing any air thatrnay be present and, thus prevent the formation of air bubbles in the stock 4which may cause breaking down of From" the foregoing. taken in connection with 'the accompanying" drawing. it4 is thought that the method will be clear to those skilled lin the art.

Iamaware that' air bags have heretofore been used in the'molding of pneumatic tires and that core pins have been employed in the making of cushion tires and that in the making of cushion tires core pins have been forced through the molds into the rubber stock. I am also aware that in the making tires core pins have been employed but in the latter casethecore placed before inflation of the an' bag takes place and stock is forced` byair bag inflation, radially between the adjacent pins and into the pe? ripher'al portion of the molding cavity. I therefore do not claim broadly thevuse of core pins orl the forcing of core pins into rubber to produce holes Ibut What I claim is:

1 The meth'odvof manufacturing pneup matic tires having ventilated treads which includes the steps of building up the carstock over the carcass periphery,

project the tread stock toapproximately, fill the tread portion infiatin the stock tread.v

the rubber treadv cassproper, applying a thick bodyof tread v placing an air bag within the carcass, placing the mass in a confining mold, closing the mold and atmosp ere to tend to cause the plastic mass ing core pins into the tread stock, and vulcanizing themass while maintaining pressure within the air ba 2. The method of building pneumatic tires having ventilated thick treads, which consists of the following steps, to-wit: building the carcass in any usual way; applying a thick layer of tread rubber over the periphery of the carcass; applying inflation -pr'essure within the carcass while restraining the outside oi the carcass and tread 'walls Within predetermined form limits; applying heat to the mass to render the rubber more or less fluid; f while the mass is under the aforesaid inflated pressure and restrained, thereby displacing tread rubber and applying a force counter to the inflation pressure laggrainstthe tread of the carcass; continuingthe application of heat until vulcanization occurs, meanwhile maintaining suflicient inflation pressure to compact the mass and finally releasing vthe restraining mass. i 4

3. The method of manufacturing pneumatic tires of the ventilated tread kind,` which method comprises the following steps, to-wit; building up the carcass proper in any desired Way; applying a thick body of tread rubber over the periphery of the carcass; inserting an air bag within the carcass and placing the mass in a vulcanizing mold; partially inflating the air bag; inserting core pins through the mold walls into the tread rubber thereby displacing tread rubber and cooperating with the action of the air bag to cause the rubber to flow into the spaces in the molding cavity walls; continuing the inflation of the air bag and heating the mold to effect vulcanization under pressure; withdrawing the core pins ;l and finally removing the vulcanized tire from the mold.

HENRY M. LAMBERT.

the air bag to` a pressure above theorcing core pins into the tread rubber- 

